Abstract

Background

In many species males face a higher predation risk than females because males display
elaborate traits that evolved under sexual selection, which may attract not only females
but also predators. Females are, therefore, predicted to avoid such conspicuous males
under predation risk. The present study was designed to investigate predator-induced
changes of female mating preferences in Atlantic mollies (Poecilia mexicana). Males of this species show a pronounced polymorphism in body size and coloration,
and females prefer large, colorful males in the absence of predators.

Results

In dichotomous choice tests predator-naïve (lab-reared) females altered their initial
preference for larger males in the presence of the cichlid Cichlasoma salvini, a natural predator of P. mexicana, and preferred small males instead. This effect was considerably weaker when females
were confronted visually with the non-piscivorous cichlid Vieja bifasciata or the introduced non-piscivorous Nile tilapia (Oreochromis niloticus). In contrast, predator experienced (wild-caught) females did not respond to the
same extent to the presence of a predator, most likely due to a learned ability to
evaluate their predators' motivation to prey.

Conclusions

Our study highlights that (a) predatory fish can have a profound influence on the expression of mating preferences
of their prey (thus potentially affecting the strength of sexual selection), and females
may alter their mate choice behavior strategically to reduce their own exposure to
predators. (b) Prey species can evolve visual predator recognition mechanisms and alter their mate
choice only when a natural predator is present. (c) Finally, experiential effects can play an important role, and prey species may learn
to evaluate the motivational state of their predators.